Multibabeel carburetor



June 1953 s. M. BICKNELL 2 MULTIBARREL CARBURETOR Filed Dec. 19, 1949 s Sheets-Sheet 1 INVENTOR. GEORGE M. BICKNELL BYg ATTORNEY June 2, 1953 e. M/BICKNELL MULTIBARREL CARBURETOR 5 Sheets-Sheet 2 Filed Dec. 19, 1949 INVENTOR. GEORGE M. BICKNELL ATTORNEY Patented June 2, 1953 7 2,640,472 MULTIBARREL CARBURETOR George M. Bicknell, St. Louis, Mo., assignor to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application December 19, 1949, Serial No. 133,930

8 Claims.

This invention relates to carburetors for internal combustion engines and consists particularly in a novel type of multibarrel carburetor.

It has been observed that a plain tube carburetor having a venturi of sufiicient size and capacity to supply the fuel requirements of an engine during wide open throttle high speed operation fails to. develop suiiicient suction during wide open throttle low speed operation.

An object of this invention is to produce a carburetor for internal combustion engines having two intake manifolds, in which the advantages of the large and small venturi may be combined. To achieve this object I provide a carburetor with two sets of mixing conduits, one for low and medium speed operation, and one to provide additional fuel for high speed operation, one of each set of mixing conduits communicating with each intake manifold.

A second object is to provide a carburetor of the type indicated above which will insure an adequate supply of fuel at all times to at least one high speed and one low speed mixture conduit.

A third object is to provide, in a carburetor of this type means for preventing opening of the high speed mixture conduits until the low-speed throttles have opened a predetermined amount and until the engine is thoroughly warmed up.

I achieve these objects by providing a carburetor of the above type having two separate fuel reservoirs, each feeding fuel to one low speed and one high speed mixture conduit; suction responsive means for controlling the high speed throttles, thermostatic means for regulating separate choke valves governing each set of mixture conduits and for preventing opening of the high speed throttles until the engine has warmed up, and additional mechanical means for preventing opening of the high speed throttles until the low speed throttles are opened a predetermine amount.

Further objects and advantages will appear from reading the specification in connection with the drawings, in which:

. Fig. 1 is a plan view partially sectionalized of a four barrel carburetor made according to my invention;

i Fig. 2 is a partial vertical section along the line Fig. 3 is a vertical section along the line 3-3 ,of Fig. 1;

Referring now to the drawing, the numeral Ill indicates a carburetor airhorn formed with separate air inlets II and I3 separated by partition l4, and admitting air, respectively, to primary mixture conduits l6 and H, and secondary mixture conduits l8 and I9.

Mixture conduits l6, l1, I8 and [9, respectively contain a series of coaxial venturis 15, the smaller of which are suspended from the mixture conduit walls by ribs 21 and 24.

Thermostatically-controlled unbalanced choke valves 22 and 23 in air inlets II and I3 regulate the admission of air into primary mixture conduits H5 and H, and secondary mixture conduits l8 and I9, respectively. Choke valves 22 and 23 are separately mounted on parallel shafts 25 and 26 which are rotatably journalled in the air inlet walls. Operation of choke valves 22 and 23 is controlled by conventional thermostatic automatic choke control devices 21 and 21a.

The lower, or outlet portion of mixture conduits I6, [1, I8 and I9 is formed in throttle body casting 28. The outlets of primary mixture conduits l6 and I! are controlled by throttle valves 29 mounted on shaft 30; throttle valves 3| mounted on parallel shaft 32, control the outlet of secondary mixture conduits l8 and I9. Throttle shafts 30 and 32 are rotatably journalled in the walls of throttle body casting 28, which is flanged at its lower end as at 34 for attachment to the intake manifolds 35 and 36.

Adjacent mixture conduits I6 and I8, and I1 and [9, respectively, are formed narrow constant level fuel reservoirs 31 and 38, containing fioats 39, operating independently needle valves 40. Liquid fuel is admitted to the carburetor through fuel inlet 4| and passes through horizontal passageways 42 formed in rib structures 43 to needle valve 40 and therethrough into reservoirs 31 and 38. Reservoirs 3i and 38 are not connected at any point but communicate independently with the atmosphere in air horn Ill through passages 44 formed in wall structure 45.

The main fuel supply for primary mixtureconduits l6 and I1 passes through main metering orifices 46 located in the bottom of reservoirs 31 and 38. Best disclosed in Fig. 5 horizontal passageways 4! connect orifices 46 with vertical passages 48' which extend upwardly through rib structures 49 formed on the inside wall of primary mixture conduits l6 and I1. Inclined passages 50 formed in ribs 2|, and nozzles 5| carry the fuel into the center of the smallest venturi [5 of primary conduits l6 and l! for discharge there- ,into byinduction. Air bleed passages 52 formed in ribs 2| connect passages 48 and nozzles 51'.

Fuel for idling is provided to primary mixture conduits I B and I7, only, through restricted tubes 54, which communicate at their lower end with passages 48 and at their upper end with horizontal passages 55, which, in turn, connect with vertical passages 57 leading to idle ports 58.

The effective area of metering orifices 46 is regulated by stepped metering pins 60, which are detachably secured at their upper ends to piston rods 6| for vertical movement therewith. Vertical movement is imparted to piston rod BI by suction piston 63 which is slidably mounted in cylinder 64 forming part of the fuel reservoir wall structure. Passageway 65 and associated passages (not shown) connect cylinder 64 with primary mixture conduits [-6 and I1 posterior to the throttle, so that movements of metering pins 80 are partly responsive to suction. I

For additional control of metering pins 60, directly responsibe to throttle movement, countershaft '56 is provided. Countershaft 66 is journalled in the Wall structure of air horn I0, which also includes cover 57 for fuel reservoirs 31 and 38 and raised enclosure 68 thereon for the metering pin operating means. Adjacent the ends of countershaft 66 metering pin operating arms Ill are secured, the outer end H of operating arms extending through a vertical slot 12 in piston rod BI and adapted to engage the upper edge of said slot for the purpose of raising the metering pins. A crank 74 is secured to the end of countershaft 68 and is connected at its outer end by a suitable link to an arm I? secured at one end of throttle shaft 30, for rotational movement therewith, so that any movement of throttle shaft is transmitted via arm 11, link I5, crank I4, countershaft 65 and arms 10 to metering pins 60, opening movements of primary throttles 29 tending to elevate metering pins 60, and throttle closing movements permitting pin 60 to drop. Covers 1 l8, sealingly secured to raised enclosures 68, complete the enclosure of the metering pin operating means and thus prevent their fouling by dust particles, grease and dirt.

Additional fuel increments for acceleration are forced into primary mixture conduits I6 and I! by a pump comprising a boss 19 formed integral with the mixture conduit wall structure, a diaphragm 80 sealingly secured against boss 19 by a cup 8 I. Spring 82, seated in cup 8i normally urges stem 84 of diaphragm 80 toward primary throttle shaft 30, which is formed with a flat-bottomed notch 85 at the point of intersection, a ball 85 being interposed between stem 84 and throttle shaft 30 to provide a rolling contact therebetween. Pumping chamber 88 communicates with fuel reservoirs 31 and 38 via inlet passage 80, and with pump nozzles 92 and 93 via passage 95 and outlet check valve 96. Notch 85 in throttle shaft 30 is so positioned that opening movements of throttle shaft 36 urge ball 8 E, stem 84, and diaphragm 8B outwardly, therefore discharging fuel from primary chamber 88.

The main fuel supply for secondary mixture conduits I8 and I9 passes through restricted orifices 98 one of which is located in each fuel reservoir. Vertical passages 99 extend upwardly and connect metering orifices 98 with inclined passages I03 formed in ribs 21. Fuel is carried by I04 into the center of the smallest extremity of throttle operating arm I06, which is secured to an end of primary throttle shaft 30.

An arm I09 is secured to the opposite end of secondary throttle shaft 32 and is formed with an inwardly extending projection I I0 for limiting closing movement of the throttle by bearing against throttle adjusting screw H2 when secondary throttle valves 3I are nearly closed; a second inwardly extending projection I I3, the function of which will be explaned in detail below; and, substantially intermediate of projections I I0 and H3, a substantially radially extending cam element H4.

A boot shaped extension I is having an arcuate end portion III concentric with throttle shaft 30 is formed on arm ll of primary throttle shaft 30 and is adapted, as primary throttles 29 move toward closed position to contact cam H4, thereby urging secondary throttles 3| toward closed position.

A crank H8 is rotatably journalled on secondary throttle shaft 32 and is normally urged into abutting relation with projection H3 of arm I09 by torsion spring I I9 so that rotary movements of arm I I8 are transmitted to secondary throttle shaft 32; arm I I8 is rotated clockwise (Fig. 3) by suction actuated bellows I20 which communicates with primary mixture conduits IE5 at I22 through tubular passage I23. One end of bellows I20 is fixed with relation to the carburetor structure and the other, movable end is connected by a suitable link I24 with the outer end of crank H8, so that under predetermined high suction conditions in primary mixture conduits I 6 and I1, when primary throttles 29 are sufficiently opened to move boot-like extension II B away from cam H4, bellows 12B draws arms H8 and I09, and secondary throttles 3| toward open position. When secondary throttles 3I reach their fully opened position, further opening movement is revented by cooperating stop lugs I22 and I22a, formed respectively on crank H3 and throttle body casting 28. A spring I2 I, secured at one end to crank I I8 and at its other end to the carburetor normally urges crank II8 counterclockwise and throttles 3| closed, in opposition to the opening effect of bellows I25. When primary throttles 29 are closed, arcuate surface I I! of primary throttle shaft arm I? bears against cam H4 of secondary throttle arm I29, thereby preventing further opening movement of arm I09 and secondary throttles 3!, any movement of crank H3 being absorbed by torsion spring H9. For preventing opening of secondary throttles 3| until the engine has warmed up, thermostatically controlled bleeder valve I 25 is interposed in the suction line I23 connecting bellows I20 and mixture conduits I6 and H. type closure member I26 slidably mounted in tubular guide I2] and has an extension I28; an arm I 30, rigidly secured at one end to choke shaft 26 is connected at its other end to extension I28 by link I29 so that closing movement of choke shaft 26, caused by thermostatic choke control 210; elevates closure member I25 and consequently, when the engine is cold, and until it becomes heated, bellows I20 is vented to atmosphere, and secondary throttles 3i remain closed.

Fig. -6 diagrammatically illustrates the manner in which the primary and secondary mixture conduits are connected to the separate intake manifolds 35 and 38, primary mixture conduit I6 and secondary mixture conduit I8 feeding manifold 35; primary mixture conduit I I and secondary mixture conduit I9 feeding manifold 36.

Valve I25 is provided with a needle pump |988 through nozzles 92.

Operation of the carburetor'is as follows: I

During idling, fuel is supplied to primary mixture conduits I6 and II from fuel chambers 31 and 38 via passages B'I'and idle ports 58. As the operator depresses the accelerator pedal (not shown), primary throttle valves 29 are moved toward opened position, and throttle opening movement is transmitted by arm 11, link I5, crank I4, shaft 66, and metering pin operating arms ID to raise metering pins 60, thus increasing the effective area of metering orifices 48 in proportion to the degree of throttle opening. As manifold suction decreases below a predetermined value, a spring (not shown) urges piston 63, rod GI, and metering pins upwardly, thus providing additional fuel to the primary mixture conduits I8 and II in proportion to decreased manifold suction. Aditional increments of fuel I are discharged into primary mixture conduits I6 and I! only during acceleration by accelerating Thus, sufficient metered fuel is provided to the primary mixing conduits I6 and I1 and through them to intake manifolds 35 and 38 for part throttle operation. During this period the arcuate extension III; on primary throttle operating arm I? contacts cam II4 on secondary throttle operating arm I09, to

lock secondary throttles 3| in the closed position. Since no manifold vacuum is transmitted to secondary mixture conduits I8 and I9, when throttles 3| are closed, secondary main nozzle I04 discharges no fuel into secondary mixture conduits I8 and I9.

If, during the warm-up period, primary throttles 29 are 'fullyiop'ened, thus moving extension IIB out of the way of cam Ila, spring I2I, acting through crank II8, projection H3, and arm I09 will hold secondary throttles 3| closed, since, until the engine is fully warmed up, automatic choke control 21a, acting through choke shaft 26, arm I30, and link I29, opens air vent valve I26, thus killing any suction in bellows I20.

As soon as the engine is warmed up, however, automatic choke control 21a closes vent valve I26 so that vacuum from "the'Venturi section of the primarymixture conduits is transmittedtobellows I20, causing link I24 to draw arm II8 clockwise in opposition to torsion spring I I9 and coil spring I2I, unless and until primary throttles 29 are sufiiciently opened to move arm extension I I6 out of the way of cam I I4, as shown in Fig. 4. When this occurs, torsion spring I|9 causes projection H3 and arm I09 to follow crank I I8, thus opening secondary throttles an amount proportional to Venturi vacuum in the primary mixture conduits. The additional fuel necessary for highspeed or full throttle operation will thus be drawn from bowl 38, through orifice 98, passages 99 and I03, and nozzle I04, into secondary mixture conduits I8 and I9, and thence into intake manifolds 35 and 36, to be added to the fuel supplied by primary mixture conduits I6 and II.

The exclusive use of all modifications of my invention as come within the scope of the appended claims is contemplated.

I claim:

1. In combination with an internal combustion engine having two intake manifolds, a carburetor having a primary set of mixture conduits for providing a fuel mixture for low and medium speed operation, a second set of mixture conduits for providing additional fuel for high speed operation, throttle valves in each of said mixture conduits, the throttle valves in said primary conduits being manually controlled, the throttle valves in said secondary mixture conduits being responsive to suction in said primary mixture conduits, separate fuel reservoirs, each fuel reservoir being connected to one primary and one secondary mixture conduit, one primary and one secondarymixture conduit communicating with each intake manifold.

2. I'd-combination with an internal combustion engine having intake manifolds, a carburetor having a primary set of mixture conduits I for providing a fuel mixture for low and medium speed operation, a second set of mixture conduits for providing additional fuel for high speed operation, throttle valves in each of said mixture conduits, the throttle valves in said primary mixture conduits being manually controlled, the throttle valves in said secondary mixture conduit being responsive to suction in said primary mixture conduits, and mechanical means associated with the throttlesin said primary mixture conduits for preventing opening of said throttles in said secondary mixture conduits until said throttles in said primary mixture conduits have opened a predetermined amount, and thermostatic means for preventing opening of said throttles in said secondary mixture conduits until the engine has warmed up. 9 i

3. In a carburetor for internal combustion engines, a primary set of mixture conduits for providing a fuel mixture for low and medium speed operation, a secondary set of mixture conduits for providing additional fuel for high speed operation, thermostatically controlled choke valves for governing the admission of air to said primary and secondary mixture'conduits, manually controlled throttle valves for regulating the discharge of fuel mixture from said primary mixture conduits, throttle valves responsive to 'manifold suction for regulating the discharge of fuel mixture from said secondary mixtureconduits, and means responsive to engine temperature for preventing opening of said secondary throttle valves until a predetermined engine temperature is reached.

4. In a carburetor for, internal Tcombustion engines, a primary setof mixture cohduits'Tor providing a fuel mixture for low and medium speed operation, a secondary set of mixture conduits for providing additional fuel for high speed operation, thermostatically controlled choke valves for governing the admission of air to said primary and secondary mixture conduits, manually controlled throttle valves for regulating the discharge of fuel mixture from said primary mixture conduits, throttle valves responsive to manifold suction for regulating the discharge of fuel mixture from said secondary mixtur conduits, two constant level fuel reservoirs, passage means including a main fuel nozzle connecting each reservoir with one primary and one secondary mixture conduit, additional passage means connecting each reservoir with one primary mixture conduit adjacent said throttle valve and means responsive to engine temperature for preventmg opening of said secondary throttle valves until a predetermined engine temperature is reached.

5. In a carburetor for internal combustion engines, a primary set of mixture conduits for providing a fuel mixture for low and medium speed operation, a secondary set of mixture conduits for providing additional fuel for high speed operation, thermostatically controlled choke valves for governing the admission of air to said primary and secondary mixture conduits, manually ach eve controlled throttle valves for regulating the discharge of ma mixture from said primary mixture conduits, throttle valves responsive to manifold suction for regulating the discharge of fuel mixture from said secondary mixture conduits,

two constant level fuel reservoirs, passage means including a main fuel nozzle connecting each reservoir with one primary and one secondary mixture conduit, additional passage means connecting each reservoir with one primary mixture,

, conduit adjacent said throttle valve, pump means :associated with said reservoirs and adapted to discharge additional fuel into said primary mixture conduits during acceleration, and an operative connection between said pump means and i-said primary throttles and means responsive to engine temperature for preventing opening of said secondary throttle valves until a predetermined engine temperature is reached.

-6. In combination with an internal combustion p engine having intake manifolds, a carburetor including a primary set of mixture conduits for providing a fuel mixture for low and medium speed operation, a secondary set of mixture conduits for providing additional fuel for high speed operation, manually controlled throttle valves for regulating said primary mixture conduits, suction responsive throttle valves for regulating said-secondary mixture conduits, means responsive to increased suction in the primary mixture conduit for opening said secondary throttle valves, passage means connecting said suction responsive means and said primary mixture conduits, valve means in said passage means communicating with the atmosphere, and thermo- .mixture conduits, a thermostatic choke control device manually controlled throttle valves in said primary conduits, suction responsive throttle valves in said secondary conduits, a suction responsive bellows for opening said secondary throttle valves responsive to decreases in suction in the primary conduits, a passage connecting said bellows and said primary conduits, a valve in said passage communicating with atmosphere, an operative connection between said valve and said thermostatic choke control device for closing said valve when a predetermined engine temperature is reached.

8. In an internal combustion engine, a carburetor having a primary mixture conduit for providing fuel for low and medium speed operation and a secondary mixture conduit for providing fuel for high speed full throttle operation, metered means for providing fuel to said conduits, a throttle valve in each of said conduits, manual means for controlling said primary throttle, a suction responsive device for controlling said secondary throttle, passage means connecting said suction responsive device with said primary mixture conduit, valve means connecting said passage means with atmosphere, thermostatic means for closing said valve means at a predetermined engine temperature, and mechanical means associated with said primary throttle for locking said secondary throttle until said primary throttle is opened a predetermined amount.

GEORGE M. BICKNELL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,095,746 Jacobs Oct. 12, 1937 2,252,120 Ericson Aug. 12, 1941 2,315,183 Bicknell et a1. Mar. 30, 1943 2,322,895 Steensen June 29, 1943 2,379,288 Ericson June 26, 1945 2,390,019 Winkler et al Nov. 27, 1945 2,391,933 Wharam et al Jan. 1, 1946 2,420,925 Wirth May 20, 1947 Strebinger Nov. 2, 1948 

